CN116154061A - High-light-efficiency flip LED chip and preparation method thereof - Google Patents

High-light-efficiency flip LED chip and preparation method thereof Download PDF

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CN116154061A
CN116154061A CN202211738876.7A CN202211738876A CN116154061A CN 116154061 A CN116154061 A CN 116154061A CN 202211738876 A CN202211738876 A CN 202211738876A CN 116154061 A CN116154061 A CN 116154061A
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gan
electrode
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aln
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刘宝琴
朱剑峰
张蔚
任飞
袁林
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NANTONG TONGFANG SEMICONDUCTOR CO Ltd
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NANTONG TONGFANG SEMICONDUCTOR CO Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/10—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
    • H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
    • H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound comprising nitride compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/20—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate
    • H01L33/22—Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

The invention discloses a high-light-efficiency flip LED chip and a preparation method thereof, wherein the chip structure comprises the following components from bottom to top: the light-emitting diode comprises a sapphire substrate, a GaN nucleation layer, an n-GaN layer, a current expansion layer, a quantum well light-emitting layer, an EBL electron blocking layer, a p-GaN layer, a reflecting layer, a transparent conductive layer, a first electrode layer, a high-reflectivity DBR layer and a second electrode layer; wherein the reflective layer material is GaN/AlN superlattice structure. According to the invention, the GaN/AlN superlattice reflecting layer is grown on the p-type gallium nitride, and is etched to form a pattern which is periodically arranged, and the etched region of the reflecting layer exposes the p-GaN layer, so that ohmic contact between the transparent conducting layer and the p-GaN layer is not affected; the structure partially reflects the light emitted to the p-GaN layer, not only increases the light reflection, but also reduces the absorption of the material to the light when the light passes through the transparent conductive layer and the electrode, and the light emitted to the electrode direction from the other part is reflected again by the high-reflectivity DBR layer, so that the light emitting efficiency of the flip LED chip is effectively improved.

Description

High-light-efficiency flip LED chip and preparation method thereof
Technical Field
The invention relates to the field of LED chips, in particular to a high-light-efficiency flip LED chip and a preparation method thereof.
Background
The flip-chip LED structure is proposed for a front-loading structure. The flip-chip light-emitting diode is characterized in that a forward-mounted LED chip is reversely buckled on a supporting substrate with high heat conductivity, so that the heat dissipation performance of the LED is improved. The serial-parallel connection of the light-emitting units is realized on the flip-chip substrate, and the wiring on the flip-chip substrate is simple and flexible, so that the technical difficulty of interconnection climbing between the isolation units in the forward-mounted product is overcome.
Due to the special structure of flip chip, the flip chip has special requirements in some manufacturing processes. In the aspect of the substrate, the light emergent surface is arranged on one side of the sapphire, so that a proper patterned substrate is manufactured before epitaxial growth, and the light emergent efficiency can be improved; in the aspect of epitaxial structure growth, the light emergent surface is changed, and the light absorption condition of each layer is different from that of a forward chip, so that the thicknesses and doping concentrations of an epitaxial buffer layer, an n-type gallium nitride layer, a multiple quantum well layer and a p-type gallium nitride layer are required to be adjusted, the epitaxial buffer layer, the n-type gallium nitride layer, the multiple quantum well layer and the p-type gallium nitride layer are suitable for the light emergent requirement of a flip chip, the light emergent efficiency is improved, and the ohmic contact requirement of the flip chip manufacturing process is met; in the aspect of chip manufacture, a high reflection layer is needed between the epitaxial layer and the electrode, so that light emitted to the direction of the electrode of the chip can be reflected back to one surface of the sapphire as much as possible, and good light-emitting efficiency is ensured.
The flip-chip LED chip in the prior art has a problem of low light extraction efficiency.
Disclosure of Invention
The invention aims to: in order to solve the problems in the prior art, the invention provides the high-light-efficiency flip LED chip and the preparation method thereof, and the light-emitting efficiency of the flip LED chip is effectively improved.
The technical scheme is as follows: the invention discloses a high-light-efficiency flip LED chip, which comprises the following structures from bottom to top: the light-emitting diode comprises a sapphire substrate, a GaN nucleation layer, an n-GaN layer, a current expansion layer, a quantum well light-emitting layer, an EBL electron blocking layer, a p-GaN layer, a light reflecting layer, a transparent conductive layer, a first electrode layer, a high-reflectivity DBR layer and a second electrode layer.
Furthermore, the reflective layer is made of GaN/AlN material, and the GaN/AlN periodically and alternately grows to form a distributed Bragg reflective layer.
Further, the growth period of the GaN/AlN material is 5-20 periods, and the first layer and the last layer are both made of GaN materials.
Further, the GaN/AlN thickness of each period is calculated and optimized according to the distributed Bragg reflection law, and the total thickness is 250-1000A.
The invention also discloses a preparation method of the high-light-efficiency flip LED chip, which comprises the steps of firstly growing in MOCVD (metal-organic chemical vapor deposition) equipment to obtain an epitaxial wafer with a complete epitaxial structure, and then preparing the flip LED chip on the epitaxial wafer.
Further, the epitaxial wafer is prepared by the following steps:
1) Growing a GaN nucleation layer on the sapphire patterned substrate;
2) Growing an n-GaN layer on the GaN nucleation layer at a high temperature;
3) Growing a current expansion layer on the n-GaN layer, wherein the current expansion layer is low-doped n-type GaN;
4) Growing an InGaN/GaN quantum well light-emitting layer on the current expansion layer;
5) Growing an EBL electron blocking layer of AlGaN material on the InGaN/GaN quantum well light-emitting layer;
6) Growing a p-GaN layer on the EBL electron blocking layer;
7) And growing a GaN/AlN reflecting layer on the p-GaN layer.
Further optimizing, the preparation steps of the epitaxial wafer are as follows:
1) Carrying out surface cleaning treatment on the sapphire pattern substrate under a high-temperature condition by using MOCVD (metal-organic chemical vapor deposition) equipment;
2) Growing a GaN nucleation layer on the sapphire patterned substrate subjected to high temperature treatment in MOCVD equipment;
3) Growing an n-GaN layer on the GaN nucleation layer in an MOCVD apparatus, n-GaThe Si doping concentration of the N layer is 5×10 18 cm -3 ～5×10 19 cm -3 ；
4) Growing a current spreading layer on the n-GaN layer in MOCVD equipment, wherein the current spreading layer is low-doped n-type GaN with Si doping concentration of 1×10 17 cm -3 ～5×10 17 cm -3 ；
5) In MOCVD equipment, a quantum well luminous layer grows on the current expansion layer, the multi-quantum well structure is formed by alternately growing well layer InGaN and barrier layer GaN, and the growth period is 5-15;
6) In MOCVD equipment, an EBL electron blocking layer is grown on a quantum well luminous layer, and the electron blocking layer is made of AlGaN and has the thickness of
Figure BDA0004030332020000021
7) Growing a p-GaN layer on the EBL electron blocking layer in MOCVD equipment, wherein the thickness of the p-GaN layer is equal to that of the electron blocking layer
Figure BDA0004030332020000022
The Mg doping concentration of the p-GaN layer was 5×10 19 cm -3 ～5×10 20 cm -3 After the epitaxial structure of the whole LED is grown, the epitaxial wafer is subjected to rapid annealing to activate the doping of the p-GaN layer; the ohmic contact of the p-GaN layer is facilitated;
8) In MOCVD equipment, a reflecting layer is grown on the p-GaN layer, the reflecting layer is made of GaN/AlN, and the GaN/AlN periodically and alternately grows to form a distributed Bragg reflecting layer; thus, the epitaxial wafer with the complete epitaxial structure is obtained.
Furthermore, the preparation steps of the flip LED are as follows:
1) Etching is carried out on the prepared epitaxial wafer, the GaN/AlN reflective layer is etched into patterns which are arranged regularly, and the etched areas of the GaN/AlN reflective layer expose the p-GaN layer;
2) Depositing a transparent conductive layer on the epitaxial wafer etched with the GaN/AlN reflective layer, wherein the transparent conductive layer is made of indium tin oxide;
3) Evaporating an electrode layer I on the transparent conductive layer, wherein the electrode layer I is made of an alloy combination of Cr/Al/Ti/Pt/Au, and the shape of the electrode is optimized according to requirements;
4) Evaporating a high-reflectivity DBR layer on the first electrode layer, wherein the DBR layer is formed by periodically and alternately growing SiO2/TiO 2;
5) Evaporating an electrode II on the high-reflectivity DBR layer again, wherein the material of the electrode II is an alloy combination of Cr/Al/Ti/Pt/Au; the high-reflectivity DBR layer is provided with a reserved through hole, the electrode layer two and the electrode layer one are in metal interconnection, and finally the flip LED chip with high light efficiency is obtained.
Further optimized, the preparation steps of the flip LED are as follows:
1) Etching is carried out on the prepared epitaxial wafer, the GaN/AlN reflecting layer is etched into patterns which are arranged regularly, the p-GaN layer is exposed out of the etched areas of the GaN/AlN reflecting layer, the sizes of the patterns which are arranged regularly are 1um to 2um, and the intervals are 1um to 2um;
2) Depositing a transparent conductive layer on the epitaxial wafer etched with the GaN/AlN reflective layer, wherein the transparent conductive layer is made of Indium Tin Oxide (ITO) and has the thickness of
Figure BDA0004030332020000031
/>
3) Evaporating an electrode layer I on the transparent conductive layer, wherein the electrode layer I is made of an alloy combination of Cr/Al/Ti/Pt/Au, and the shape of the electrode is optimized according to requirements;
4) Evaporating DBR layers with high reflectivity on the first electrode layer, wherein the DBR layers are formed by periodically and alternately growing SiO2/TiO2, the growth period is 20-50 periods, and the total thickness is 1-5 um;
5) Evaporating an electrode II on the high-reflectivity DBR layer again, wherein the material of the electrode II is an alloy combination of Cr/Al/Ti/Pt/Au; the high reflection DBR layer is provided with a reserved through hole for connecting the electrode layer two with the electrode layer one; and finally obtaining the flip LED chip with high light efficiency.
The beneficial effects are that: the invention has the following advantages:
the GaN/AlN superlattice reflecting layer grows on the p-type gallium nitride, the reflecting layer is etched to form a pattern which is periodically arranged, and the p-GaN layer exposed out of the etched area of the reflecting layer forms good ohmic contact with the transparent conducting layer; the structure partially reflects the light emitted to the p-GaN layer, not only increases the light reflection, but also reduces the absorption of the material to the light when the light passes through the transparent conductive layer and the electrode, and the light emitted to the electrode direction from the other part is reflected again by the high-reflectivity DBR layer, so that the light emitting efficiency of the flip LED chip is effectively improved.
Drawings
FIG. 1 is a schematic diagram of a high light efficiency flip LED chip according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for epitaxial structure growth of a flip LED chip according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method of fabricating a flip LED chip according to an embodiment of the present invention;
wherein: the light-emitting diode comprises a 01-sapphire substrate, a 02-GaN nucleation layer, a 03-n-GaN layer, a 04-current expansion layer, a 05-quantum well light-emitting layer, a 06-EBL electron blocking layer, a 07-p-GaN layer, a 08-reflecting layer, a 09-transparent conductive layer, a 10-electrode layer I, a 12-high-reflectivity DBR layer and a 13-electrode layer II.
Detailed Description
Referring to fig. 1-3, the invention provides a flip-chip LED chip with high light efficiency and a method for manufacturing the same, wherein the chip structure is as shown in fig. 1, and comprises from bottom to top: a sapphire substrate 01, a GaN nucleation layer 02, an n-GaN layer 03, a current expansion layer 04, a quantum well light-emitting layer 05, an EBL electron blocking layer 06, a p-GaN layer 07, a reflecting layer 08, a transparent conductive layer 09, an electrode layer one 10, a high-reflectivity DBR layer 12 and an electrode layer two 13; wherein the reflective layer 08 is a superlattice structure of GaN/AlN material.
Specifically, the reflective layer 08 is a distributed Bragg reflective layer formed by periodically and alternately growing GaN/AlN; according to the required luminous wavelength of the LED, the Bragg reflection is calculated through a law of division and the growth thickness of each layer of GaN/AlN is optimized; the growth period of GaN/AlN is 5-20 periods, the first layer and the last layer are both made of GaN material, and the total growth thickness of the final reflecting layer 08 is between
Figure BDA0004030332020000041
By epitaxially growing the light-reflecting layer on top of the p-GaN layer08, and etch the reflecting layer 08, form the pattern of periodic arrangement, the area etched out of reflecting layer 08 exposes p-GaN layer, transparent conductive layer and p-GaN layer can still form good ohmic contact; the structure partially reflects the light emitted to the p-GaN layer, not only increases the light reflection, but also reduces the absorption of the material to the light when the light passes through the transparent conductive layer and the electrode, and the light emitted to the electrode direction from the other part is reflected again by the high-reflectivity DBR layer, so that the light emitting efficiency of the flip LED chip is effectively improved.
In the preparation method of the flip LED chip with high light efficiency, the embodiment specifically provides the following process production flow.
The epitaxial structure growth method of the flip LED chip with high light efficiency is shown by referring to a process flow chart of FIG. 2, and specifically comprises the following steps:
1) Carrying out surface cleaning treatment on the sapphire pattern substrate 01 by using metal-organic chemical vapor deposition equipment MOCVD (metal organic chemical vapor deposition), optionally raising the temperature of a cavity to 1050 ℃ in a hydrogen atmosphere, and maintaining the temperature for 10 minutes;
2) In MOCVD equipment, growing a GaN nucleation layer 02 on a sapphire patterned substrate 01 subjected to high-temperature treatment, wherein the GaN nucleation layer 02 firstly undergoes three-dimensional large-particle growth and then transits to two-dimensional high-quality film growth to obtain a GaN film layer with lower defect density;
3) In MOCVD apparatus, an n-GaN layer 03 is grown on a GaN nucleation layer 02 at high temperature, optionally at 1050 ℃ to a thickness of about 2um with a Si doping concentration of 5×10 18 cm -3 ～5×10 19 cm -3 ；
4) In MOCVD equipment, growing current expansion layer 04 on n-GaN layer 03, optionally low-doped n-type GaN material, thickness of current expansion layer 04 is 0.2-0.5 um, and Si doping concentration is 1×10 17 cm -3 ～5×10 17 cm -3 ；
5) In MOCVD equipment, a quantum well luminescent layer 05 is grown on a current expansion layer 04, a multi-quantum well structure is formed by alternately growing well layer InGaN and barrier layer GaN, and the thickness of the well layer InGaN is selected as follows
Figure BDA0004030332020000051
The thickness of the barrier layer GaN is->
Figure BDA0004030332020000052
The alternate growth period is 5-15;
6) In MOCVD equipment, an EBL electron blocking layer 06 is grown on the quantum well luminescent layer 05, and the material of the electron blocking layer 06 is AlGaN, wherein the Al content is 10-30%, and the growth thickness of the electron blocking layer 06 is
Figure BDA0004030332020000055
7) In the MOCVD apparatus, a p-GaN layer 07 is grown on the EBL electron blocking layer 06, and optionally, the thickness of the p-GaN layer 07 is as follows
Figure BDA0004030332020000054
The Mg doping concentration is 5 multiplied by 10 19 cm -3 ～5×10 20 cm -3 And after the epitaxial structure of the whole LED is grown, the epitaxial wafer needs to be rapidly annealed to activate the doping of the p-GaN layer 07, which is beneficial to improving the ohmic contact of the p-GaN layer 07;
8) In MOCVD equipment, a reflective layer 08 is grown on a p-GaN layer 07, the reflective layer 08 is made of GaN/AlN, the GaN/AlN periodically and alternately grows to form a distributed Bragg reflective layer, and the first layer and the last layer are made of GaN materials; alternatively, the growth period of GaN/AlN is 5-20 periods, the thickness of GaN/AlN in each period is calculated and optimized according to the distributed Bragg reflection law, and the total growth thickness of the reflecting layer 08 is between
Figure BDA0004030332020000053
Next, referring to the process flow chart of fig. 3, the chip preparation method of the flip-chip LED chip with high light efficiency is shown as follows:
1) Carrying out MESA etching on the prepared epitaxial wafer to an n-GaN layer and etching a table top of an n electrode, wherein the specific method comprises the steps of firstly cleaning the epitaxial wafer to remove surface dirt, then carrying out spin coating, exposure and development on a yellow light area to obtain a mask layer of the MESA on the surface of the epitaxial wafer, carrying out dry etching by using ICP equipment to etch an area which is not covered by the mask layer to the n-GaN layer, thereby obtaining the table top of the n electrode, simultaneously obtaining a cutting channel between core particles, and cleaning to remove residual photoresist on the surface, namely the mask layer after etching is finished;
2) Etching the GaN/AlN reflective layer 08 on the epitaxial wafer to form a pattern in regular arrangement, wherein the etched area of the GaN/AlN reflective layer 08 exposes the p-GaN layer; the specific method comprises the steps of carrying out spin coating, exposure and development on a yellow light area, forming a required pattern mask layer on the surface of an epitaxial wafer, namely the reflective layer 08, and then etching the reflective layer 08 by using ICP equipment to obtain a preset pattern; alternatively, the regularly arranged patterns may be cone patterns, cylindrical patterns, or other patterns, where the cone patterns are selected in this embodiment, and the sizes of the regularly arranged patterns are 1 um-2 um, and the pitches are 1 um-2 um; then cleaning to remove the mask layer;
3) Depositing a transparent conductive layer 09 on the epitaxial wafer etched with the GaN/AlN reflective layer 08, wherein the transparent conductive layer is made of indium tin oxide ITO with thickness
Figure BDA0004030332020000061
The specific preparation method comprises the steps of adopting vacuum magnetron sputtering equipment to perform ITO film evaporation to obtain a transparent conductive layer 09 with a preset thickness; then carrying out spin coating, exposure and development on the yellow light area, obtaining a required pattern on the transparent conductive layer 09, exposing the table surface of the n electrode and the cutting channel of the core particle, removing the ITO layer on the table surface of the n electrode and the cutting channel of the core particle by adopting wet etching, then cleaning to remove the mask layer remained on the surface, covering the p electrode table surface of the core particle obtained by the steps by the ITO layer, and forming good ohmic contact on the contact area of the p-GaN layer 07 and the ITO layer 09; since the reflective layer 08 is regularly arranged above the p-GaN layer 07, the contact area between the p-GaN layer 07 and the ITO layer 09 is also regularly arranged, which is also advantageous for uniform current spreading;
4) Evaporating an electrode layer I10 (p electrode and n electrode respectively) on a transparent conductive layer 09, wherein the electrode layer I is made of an alloy combination of Cr/Al/Ti/Pt/Au, and the electrode shape can be optimally designed according to the requirement;
5) Evaporating DBR layers 12 with high reflectivity on the surface of the wafer, wherein the structure of the DBR layers 12 is that SiO2/TiO2 materials are periodically and alternately grown, the growth period is 20-50 periods, and the total thickness is 1-5 um; after the DBR film layer is plated, photoresist evening, exposure and development are carried out in a yellow light area, ICP dry etching is adopted, and then a mask layer remained on the surface is cleaned off, so that through holes reserved on the p electrode and the n electrode are obtained, and metal interconnection is carried out between the p electrode and the second electrode;
6) Evaporating a second electrode 13 (p-pad and n-pad respectively) on the high-reflectivity DBR layer 12, wherein the second electrode layer is made of an alloy combination of Cr/Al/Ti/Pt/Au; the specific method comprises the steps of carrying out spin coating, exposure and development on a yellow light region, forming a required electrode pattern on the DBR layer 12, carrying out film evaporation of the electrode layer II by using magnetron sputtering equipment, tearing off gold, removing the photoresist, obtaining the electrode layer II 10 (p-pad and n-pad respectively) with a preset pattern, and forming good metal interconnection between the electrode layer II and the electrode layer I through the through holes reserved on the high-reflectivity DBR layer 12.
According to the invention, the GaN/AlN superlattice reflecting layer is grown on the p-type gallium nitride, and etched to form a pattern which is periodically arranged, and the p-GaN layer exposed from the etched area of the reflecting layer forms good ohmic contact with the transparent conducting layer; the structure partially reflects the light emitted to the p-GaN layer, not only increases the light reflection, but also reduces the absorption of the material to the light when the light passes through the transparent conductive layer and the electrode, and the light emitted to the electrode direction from the other part is reflected again by the high-reflectivity DBR layer, so that the light emitting efficiency of the flip LED chip is effectively improved.

Claims (9)

1. The high-light-efficiency flip LED chip is characterized by comprising the following structures from bottom to top: the light-emitting diode comprises a sapphire substrate, a GaN nucleation layer, an n-GaN layer, a current expansion layer, a quantum well light-emitting layer, an EBL electron blocking layer, a p-GaN layer, a light reflecting layer, a transparent conductive layer, a first electrode layer, a high-reflectivity DBR layer and a second electrode layer.
2. The high light efficiency flip-chip LED chip of claim 1, wherein: the reflective layer is made of GaN/AlN material, and the GaN/AlN periodically and alternately grows to form a distributed Bragg reflective layer.
3. The high light efficiency flip-chip LED chip of claim 2, wherein: the growth period of the GaN/AlN material is 5-20 periods, and the first layer and the last layer are both made of GaN materials.
4. A high light efficiency flip-chip LED chip as recited in claim 3, wherein: the GaN/AlN thickness of each period is calculated and optimized according to the distributed Bragg reflection law, and the total thickness is 250-1000A.
5. A preparation method of the high-light-efficiency flip LED chip is characterized in that the flip LED chip is firstly grown in MOCVD (metal-organic chemical vapor deposition) equipment to obtain an epitaxial wafer with a complete epitaxial structure, and then the flip LED chip is prepared on the epitaxial wafer.
6. The preparation method of the high-light-efficiency flip-chip LED chip as claimed in claim 5, wherein the preparation steps of the epitaxial wafer are as follows:
1) Growing a GaN nucleation layer on the sapphire patterned substrate;
2) Growing an n-GaN layer on the GaN nucleation layer at a high temperature;
3) Growing a current expansion layer on the n-GaN layer, wherein the current expansion layer is low-doped n-type GaN;
4) Growing an InGaN/GaN quantum well light-emitting layer on the current expansion layer;
5) Growing an EBL electron blocking layer of AlGaN material on the InGaN/GaN quantum well light-emitting layer;
6) Growing a p-GaN layer on the EBL electron blocking layer;
7) And growing a GaN/AlN reflecting layer on the p-GaN layer.
7. The preparation method of the high-light-efficiency flip-chip LED chip as claimed in claim 6, wherein the preparation steps of the epitaxial wafer are as follows:
1) Carrying out surface cleaning treatment on the sapphire pattern substrate under a high-temperature condition by using MOCVD (metal-organic chemical vapor deposition) equipment;
2) Growing a GaN nucleation layer on the sapphire patterned substrate subjected to high temperature treatment in MOCVD equipment;
3) Growing an n-GaN layer on the GaN nucleation layer in an MOCVD apparatus, wherein the Si doping concentration of the n-GaN layer is 5×10 18 cm -3 ～5×10 19 cm -3 ；
4) Growing a current spreading layer on the n-GaN layer in MOCVD equipment, wherein the current spreading layer is low-doped n-type GaN with Si doping concentration of 1×10 17 cm -3 ～5×10 17 cm -3 ；
5) In MOCVD equipment, a quantum well luminous layer grows on the current expansion layer, the multi-quantum well structure is formed by alternately growing well layer InGaN and barrier layer GaN, and the growth period is 5-15;
6) In MOCVD equipment, an EBL electron blocking layer is grown on a quantum well luminous layer, and the electron blocking layer is made of AlGaN and has the thickness of
Figure FDA0004030332010000021
7) Growing a p-GaN layer on the EBL electron blocking layer in MOCVD equipment, wherein the thickness of the p-GaN layer is equal to that of the electron blocking layer
Figure FDA0004030332010000022
The Mg doping concentration of the p-GaN layer was 5×10 19 cm -3 ～5×10 20 cm -3 After the epitaxial structure of the whole LED is grown, the epitaxial wafer is subjected to rapid annealing to activate the doping of the p-GaN layer;
8) In MOCVD equipment, a reflecting layer is grown on the p-GaN layer, the reflecting layer is made of GaN/AlN, and the GaN/AlN periodically and alternately grows to form a distributed Bragg reflecting layer; thus, the epitaxial wafer with the complete epitaxial structure is obtained.
8. The method for manufacturing the flip-chip LED with high light efficiency according to claim 5, wherein the steps for manufacturing the flip-chip LED are as follows:
1) Etching is carried out on the prepared epitaxial wafer, the GaN/AlN reflective layer is etched into patterns which are arranged regularly, and the etched areas of the GaN/AlN reflective layer expose the p-GaN layer;
2) Depositing a transparent conductive layer on the epitaxial wafer etched with the GaN/AlN reflective layer, wherein the transparent conductive layer is made of indium tin oxide;
3) Evaporating an electrode layer I on the transparent conductive layer, wherein the electrode layer I is made of an alloy combination of Cr/Al/Ti/Pt/Au, and the shape of the electrode is optimized according to requirements;
4) Evaporating a high-reflectivity DBR layer on the first electrode layer, wherein the DBR layer is formed by periodically and alternately growing SiO2/TiO 2;
5) Evaporating an electrode II on the high-reflectivity DBR layer again, wherein the material of the electrode II is an alloy combination of Cr/Al/Ti/Pt/Au; the high-reflectivity DBR layer is provided with a reserved through hole, the electrode layer two and the electrode layer one are in metal interconnection, and finally the flip LED chip with high light efficiency is obtained.
9. The method for manufacturing the flip-chip LED with high light efficiency according to claim 8, wherein the steps for manufacturing the flip-chip LED are as follows:
1) Etching is carried out on the prepared epitaxial wafer, the GaN/AlN reflecting layer is etched into patterns which are arranged regularly, the p-GaN layer is exposed out of the etched areas of the GaN/AlN reflecting layer, the sizes of the patterns which are arranged regularly are 1um to 2um, and the intervals are 1um to 2um;
2) Depositing a transparent conductive layer on the epitaxial wafer etched with the GaN/AlN reflective layer, wherein the transparent conductive layer is made of Indium Tin Oxide (ITO) and has the thickness of
Figure FDA0004030332010000023
3) Evaporating an electrode layer I on the transparent conductive layer, wherein the electrode layer I is made of an alloy combination of Cr/Al/Ti/Pt/Au, and the shape of the electrode is optimized according to requirements;
4) Evaporating DBR layers with high reflectivity on the first electrode layer, wherein the DBR layers are formed by periodically and alternately growing SiO2/TiO2, the growth period is 20-50 periods, and the total thickness is 1-5 um;
5) Evaporating an electrode II on the high-reflectivity DBR layer again, wherein the material of the electrode II is an alloy combination of Cr/Al/Ti/Pt/Au; the high reflection DBR layer is provided with a reserved through hole for connecting the electrode layer two with the electrode layer one;
and finally obtaining the flip LED chip with high light efficiency.
CN202211738876.7A 2022-12-30 2022-12-30 High-light-efficiency flip LED chip and preparation method thereof Pending CN116154061A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116565093A (en) * 2023-07-11 2023-08-08 江西兆驰半导体有限公司 LED chip preparation method and LED chip

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116565093A (en) * 2023-07-11 2023-08-08 江西兆驰半导体有限公司 LED chip preparation method and LED chip

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